Mar-resistant oligomeric-based coatings

ABSTRACT

A curable coating composition comprising functionalized oligomer components I and ii which cross-link at cure to form a three-dimensional network having chains of substantially uniform, controllable molecular weight between cross-links; oligomers i and ii having weight average molecular weights not exceeding about 3,000, a polydispersity for (i) not exceeding about 1.5, and functionalities that react with one another to cross-link I and ii at cure to yield coatings with an excellent balance of hardness and mar resistance.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a curable coating compositionparticularly useful as a topcoat in multi-layered coating systems.

[0002] Basecoat-clearcoat systems have found wide acceptance in the pastdecade as automotive finishes. Continuing effort has been directed tosuch coating systems to improve the overall appearance, the clarity ofthe topcoat, and the resistance to deterioration. Further effort hasbeen directed to the development of coating compositions having lowvolatile organic content (VOC). A continuing need exists for coatingformulations which provide outstanding performance characteristics afterapplication, and particularly mar-resistance and resistance toenvironmental etching. Heretofore, mar-resistant coatings were attainedby softening the coating, which depreciates other performancecharacteristics. The instant invention overcomes this problem.

SUMMARY OF THE INVENTION

[0003] This invention concerns a curable coating composition of a binderin an organic solvent, the composition having a volatile organic contentnot exceeding about 0.4 kilograms per liter, comprising:

[0004] i) a binder selected from a linear or branched cycloaliphaticmoiety-containing oligomer or blend of oligomers with a weight averagemolecular weight not exceeding about 3,000, a polydispersity notexceeding about 1.5 and functionality A or A plus B; and

[0005] ii) an optional oligomeric crosslinker or blend of crosslinkerswith a weight average molecular weight not exceeding about 3,000 andfunctionality C or C plus D;

[0006] components i and ii reacting at cure to form a three-dimensionalnetwork having chains of substantially uniform, controllable molecularweight between crosslinks.

[0007] Preferred functionalities in oligomeric components i and ii areas follows: COMPONENT (i) COMPONENT (ii) A = hydroxyl C = isocyanate A =hydroxyl C = melamine A = anhydride C = epoxy A = anhydride C = epoxy; D= hydroxyl A = acid C = epoxy A = acid; B = hydroxyl C = epoxy; D =melaniine A = epoxy C = isocyanate A = epoxy; B = hydroxyl C =isocyanate A = aldimine C = isocyanate A = aldimine; B = hydroxyl C =isocyanate A = ketiinine C = isocyanate A = ketimine; B = hydroxyl C =isocyanate A = silane C = silane A = silane; B = hydroxyl C = melamine A= silane; B = hydroxyl C = isocyanate A = silane; B = epoxy C = acid; D= melamine

[0008] The compositions of this invention, comprising (i) when (i) isself-crosslinking, or, (i) plus (ii), may also contain up to a total ofabout 30% based on the total binder of a noncyclic oligomer and/or anacrylic polymer and/or a dispersed macromolecular polymer as describedin more detail hereafter. This invention also concerns a method forcoating a substrate comprising applying the disclosed compositionthereto and curing the composition; as well as a substrate coated withthe composition. The term “isocyanate(s)” employed herein includesblocked isocyanate(s) as well.

DETAILS OF THE INVENTION

[0009] The compositions of this invention form structured polymernetworks of high hardness and excellent mar resistance. Thefunctionality of these oligomers is predictably (nonrandomly) locatedversus polymers in which functionality is randomly distributed and whosepolydispersities generally exceed 2.0. By “polydispersity” is meantweight average molecular weight divided by number average molecularweight, both measured by gel permeation chromatography. In compositionsof this invention, molecular weight between crosslinks can be controlledto form more uniform networks minimizing short, embrittling lengths andlong, softening lengths; minimizing soluble non-functional materials inthe network and maximizing the toughness of the films (energy to break).These systems develop open networks with high molecular weight betweencrosslinks, vs. polymeric systems, at relatively high Tg's.

[0010] The Tg of these systems can be controlled to give a maximumbalance of mar; hardness, durability, and etch. In measuring Tg ofcrosslinked films made from compositions of this invention using dynamicmechanical analysis, the Tg regime is characterized by a steep slopeversus a gradual slope for a random system based on polymers. Thereactivity of these systems is such that complete reaction is attainableto minimize hydrophilic groups. These systems are typically baked at120° to 141° C. (250° to 285° F.), but can be cured at lowertemperatures through the use of more reactive groups and catalysis.

[0011] Representative of the functionalized oligomers that can beemployed as component i or ii are the following:

[0012] Acid Oligomers: The reaction product of multifunctional alcoholssuch as pentaerythritol, hexanediol, trimethylol propane, and the like,with cyclic monomeric anhydrides such as hexahydrophthalic anhydride,methylhexahydrophthalic anhydride, and the like.

[0013] Hydroxyl Oligomers: The above acid oligomers further reacted withmonofunctional epoxies such as butylene oxide, propylene oxide, and thelike.

[0014] Anhydride Oligomers: The above acid oligomers further reactedwith ketene.

[0015] Silane Oligomers: The above hydroxyl oligomers further reactedwith isocyanato propyl trimethoxy silane.

[0016] Epoxy Oligomers: The diglycidyl ester of cyclohexane dicarboxylicacid, such as AralditeÒ CY-184 from Ciba Geigy, and cycloaliphaticepoxies, such as ERLÒ-4221, and the like from Union Carbide.

[0017] Isocyanate Oligomers: The isocyanurate trimer of hexamethylenediisocyanate, DESMODURÒ 3300 from Bayer or Tolonate HDTâ fromRhone-Poulenc, and the isocyanurate trimer of isophorone diisocyanate,and the like.

[0018] Aldimine Oligomers: The reaction product of isobutyraldehyde withdiamines such as isophorone diamine, and the like.

[0019] Ketimine Oligomers: The reaction product of methyl isobutylketone with diamines such as isophorone diamine.

[0020] Melamine Oligomers: Commercially available melamines such asCYMELÒ 1168 from Cytec Industries, and the like.

[0021] AB-Funtionalized Oligomers: Acid/hydroxyl functional oligomersmade by further reacting the above acid oligomers with 50%, based onequivalents, of monofunctional epoxy such as butylene oxide or blends ofthe hydroxyl and acid oligomers mentioned above or any other blenddepicted above.

[0022] CD-Functionalized Crosslinkers: Epoxy/hydroxyl functionalcrosslinkers such as the polyglycidyl ether of Sorbitol DCE-3586 fromDixie Chemical or blends of the hydroxyl oligomers and epoxycrosslinkers mentioned above or any other blend as depicted above.

[0023] The compositions of this invention may additionally contain up to30% by weight of binder of a noncyclic oligomer, i.e., one that islinear or aromatic. Such noncyclic oligomers can include, for instance,succinic anhydride- or phthalic anhydride-derived moieites in the “AcidOligomers” such as described above.

[0024] Preferred oligomers (i) have weight average molecular weight notexceeding about 3,000 with a polydispersity not exceeding about 1.5;more preferred oligomers have molecular weight not exceeding about 2,500and polydispersity not exceeding about 1.4; most preferred oligomershave molecular weight not exceeding about 2,200, and polydisperity notexceeding about 1.25. The compositions of this invention can comprise100% by weight of component (i) when (i) is a self-crosslinker. Moretypically, compositions will comprise 20-80 weight percent of (i),preferably 30 to 70 weight percent and more preferably 40 to 60 weightpercent, with the balance being (ii).

[0025] The present coating composition can further comprise a functionalamount of catalyst, generally about 0.1 to 5 weight percent, based onthe weight of solids in the formulation. A wide variety of catalysts canbe used, such as dibutyl tin dilaurate for isocyanate based reactions,tertiary amines such as triethylenediamine or phosphonium basedcatalysts for epoxy reaction and sulfonic acids, such as dodecylbenzenesulfonic acid for melamine reactions.

[0026] The coating compositions of the present invention are formulatedinto high solids coating systems dissolved in at least one solvent. Thesolvent is usually organic. Preferred solvents include aromatichydrocarbons such as petroleum naphtha or xylenes; ketones such asmethyl amyl ketone, methyl isobutyl ketone, methyl ethyl ketone oracetone; esters such as butyl acetate or hexyl acetate; and glycol etheresters such as propylene glycol monomethyl ether acetate.

[0027] The coating compositions of the present invention can alsocontain up to 30% of total binder of an acrylic polymer of weightaverage molecular weight greater than 3,000, or a conventional polyestersuch as SCDÒ-1040 from Etna Product Inc. for improved appearance, sagresistance, flow and leveling and such. The acrylic polymer can becomposed of typical monomers such as acrylates, methacrylates, styreneand the like and functional monomers such as hydroxy ethyl acrylate,glycidyl methacrylate, or gamma methacrylyl propyl trimethoxy silane andthe like.

[0028] The coating compositions of the present invention can alsocontain up to 30% of total binder of a dispersed acrylic component whichis a polymer particle dispersed in an organic media, which particle isstabilized by what is known as steric stabilization. Hereafter, thedispersed phase or particle, sheathed by a steric barrier, will bereferred to as the “macromolecular polymer” or “core”. The stabilizerforming the steric barrier, attached to this core, will be referred toas the “macromonomer chains” or “arms”.

[0029] The dispersed polymer contains about 10 to 90%, preferably 50 to80%, by weight, based on the weight of the dispersed polymer, of a highmolecular weight core having a weight average molecular weight of about50,000 to 500,000. The preferred average particle size is 0.1 to 0.5microns. The arms, attached to the core, make up about 10 to 90%,preferably 10 to 59%, by weight of the dispersed polymer, and have aweight average molecular weight of about 1,000 to 30,000, preferably1,000 to 10,000.

[0030] The macromolecular core of the dispersed polymer is comprised ofpolymerized acrylic monomer(s) optionally copolymerized withethylenically unsaturated monomer(s). Suitable monomers include styrene,alkyl acrylate or methacrylate, ethylenically unsaturated monocarboxylicacid, and/or silane-containing monomers. Such monomers as methylmethacrylate contribute to a high Tg (glass transition temperature)dispersed polymer, whereas such “softening” monomers as butyl acrylateor 2-ethylhexylacrylate contribute to a low Tg dispersed polymer. Otheroptional monomers are hydroxyalkyl acrylates or methacrylates oracrylonitrile. Optionally, the macromolecular core can be crosslinkedthrough the use of diacrylates or dimethacrylates such as allylmethacrylate or post reaction of hydroxyl moieties with polyfunctionalisocyanates.

[0031] The macromonomer arms attached to the core can containpolymerized monomers of alkyl methacrylate, alkyl acrylate, each having1 to 12 carbon atoms in the alkyl group, as well as glycidyl acrylate orglycidyl methacrylate or ethylenically unsaturated monocarboxylic acidfor anchoring and/or crosslinking. Typically useful hydroxy-containingmonomers are hydroxy alkyl acrylates or methacrylates as describedabove.

[0032] The coating compositions of the present invention can alsocontain conventional additives such as pigments, stabilizers, rheologycontrol agents, flow agents, toughening agents and fillers. Suchadditional additives will, of course, depend on the intended use of thecoating composition. Fillers, pigments, and other additives that wouldadversely effect the clarity of the cured coating will not be includedif the composition is intended as a clear coating.

[0033] The coating compositions are typically applied to a substrate byconventional techniques such as spraying, electrostatic spraying, rollercoating, dipping or brushing. The present formulations are particularlyuseful as a clear coating for outdoor articles, such as automobile andother vehicle body parts. The substrate is generally prepared with aprimer and or a color coat or other surface preparation prior to coatingwith the present compositions.

[0034] After application to a substrate, the present compositions can becured by heating to a temperature of about 120°-150° C. for a period ofabout 15 to 90 minutes.

[0035] The present invention is further illustrated by the followingProcedures and Examples, in which parts and percentages are by weightunless otherwise indicated. VOC determinations are made by the procedureof ASTM method D3960.

PROCEDURE 1 TETRA HYDROXYL FUNCTIONAL OLIGOMER

[0036] Preparation of Acid Oligomer

[0037] To a 12-liter flask fitted with an agitator, condenser, heatingmantle, nitrogen inlet, thermocouple and an addition port was added2447.2 gms of propylene glycol monomethylether acetate, 792.4 gms ofpentaerythritol and 1.36 gms of triethylamine. The reaction mixture wasagitated and heated to 140° C. under a nitrogen blanket at which time3759 gms of methyl hexahydrophthalic anhydride was added over 6 hrs. Thereaction mixture was then held at 140° C. until no anhydride bands wereobserved on an infrared spectroscopic trace.

[0038] Preparation of Diol

[0039] To a 5-liter flask fitted with an agitator, condenser, heatingmantle, nitrogen inlet, thermocouple and an addition port was added2798.4 gms of acid oligomer prepared above and 2.76 gms oftriethylamine. The mixture was agitated and heated to 60° C. undernitrogen. Then, 696.9 gms of 1,2-epoxy butane was added over 120 mins,after which the temperature was raised to 105° C. and held at thattemperature until the acid number dropped to about 10 or less. Percentweight solids were 71.5, Gardner viscosity V, number average molecularweight 895 and weight average molecular weight 1022 as determined by GPC(polystyrene standard).

PROCEDURE 2 DI HYDROXYL FUNCTIONAL OLIGOMER

[0040] Preparation of Acid Oligomer

[0041] To a 12-liter flask fitted with an agitator, condenser, heatingmantle, nitrogen inlet, thermocouple and an addition port was added2434.5 gms of propylene glycol monomethylether acetate, 1222.5 gms ofhexane diol and 1.37 gms of triethylamine. The reaction mixture wasagitated and heated to 140° C. under a nitrogen blanket at which time3341.6 gms of methyl hexahydrophthalic anhydride was added over 6 hrs.The reaction mixture was then held at 140° C. until no anhydride bandswere observed on an infrared spectroscopic trace.

[0042] Preparation of Oligomeric Diol

[0043] To a 5-liter flask fitted with an agitator, condenser, heatingmanntle, nitrogen inlet, thermocouple and an addition port was added2020.4 gms of acid oligomer prepared above and 2.45 gms oftriethylamine. The mixture was agitated and heated to 60° C. undernitrogen. Then, 478.3 gms of 1,2-epoxy butane was added over 120 mins,after which the temperature was raised to 105° C. and held at thattemperature until the acid number dropped to about 10 or less. Percentweight solids were 69.5, Gardner viscosity A, number average molecularweight 679 and weight average molecular weight 770 as determined by GPC(polystyrene standard).

PROCEDURE 3

[0044] HYDROXYL/SILANE OLIGOMER The oligomer from Procedure 2 wasfurther 250 reacted by mixing di hydroxyl functional oligomer isocyanatopropyl trimethoxy silane 60.9 1% dibutyl tin dilaurate in methylethyl0.25 ketone (MEK)

[0045] The above mixture was heated at 60° C. for 3 days. The completionof the reaction was monitored by infra red spectroscopy. The reactionwas complete when there was essentially no isocyanate absorption in theIR.

PROCEDURE 4 ANHYDRIDE OLIGOMER

[0046] The anhydride oligomer was prepared from a tetra-functionalhalf-acid ester. The following constituents were charged to a reactionvessel equipped with a heating mantle, reflux condenser; thermometer,nitrogen inlet, and stirrer: Parts by Weight Portion I pentaerythritol478.0 methyl hexahydrophthalic anhydride 2250.0 triethylamine 0.5Portion II xylol (135°-145° C.) 2250.0 Total 4978.5

[0047] Portion 1 was charged into the reaction vessel, heated to 180° C.under a nitrogen blanket and held for 30 minutes. After the hold period,the reaction mixture was cooled and Portion 2 added.

[0048] The solution prepared above was used to make a linear pendantanhydride. The solution was charged into a 5 L flask equipped with astirrer and a gas inlet tube. The gas inlet tube was attached to aketene generator similar to the one described by Williams et al in theJournal of Organic Chemistry 5, 122, 1940. Ketene was bubbled throughthe solution until all of the acid groups were converted to anhydridegroups. Solvent was then removed under vacuum to give a linear pendantanhydride with the following characteristics:

[0049] percent weight solids: 78.0

[0050] anhydride eq. wt.: 329±4 (on solution basis)

[0051] acid eq. wt.: 6176±1323 (on solution basis)

[0052] weight average mol wt.=1100.

EXAMPLE 1 ISOCYANATE CLEAR

[0053] Parts by Weight Part I tetra hydroxyl functional oligomer 217.71(Procedure 1) di hydroxyl functional oligomer 149.24 (Procedure 2)propylene glycol mono methyl ether 26.14 acetate (PM acetate) TinuvinÒ384 (UV screener from Ciba Geigy) 8.94 TinuvinÒ 292 (hindered aminelight stabilizer 6.72 from Ciba Geigy) 10% BYK-301Ò (flow additive fromBYK Chemie) 1.78 in PM acetate 10% di butyl tin dilaurate in methylethyl ketone 1.12 butyl acetate 52.27 Part II TolonateÒ HDT(isocyanurate trimer of 192.23 hexamethylene diisocyanate fromRhone-Poulenc)

[0054] This coating was sprayed over a black waterborne basecoat whichhad already received a warm air flash of 5 min at 82° C (180° F). Thecoating was cured for 30 min at 141° C. (285° F.). The coating exhibitedexcellent appearance, hardness and mar resistance. This coatingexhibited higher hardness and significantly better mar resistance than astandard coating made at a similar final film Tg using a routinehydroxyl functional acrylic polymer (6,000 weight average molecularweight polymer with 32% hydroxy ethyl acrylate). The acrylic resin wassubstituted for the oligomer on an equivalent basis. OLIGOMERIC PROPERTY2K CLEAR POLYMERIC 2K CLEAR Glass Transition 42.7° C. 48.1° C.Temperature¹ Hardness² 141 N/mm² 130 N/mm² Wet mar³ 80% 50.6% Dry mar⁴94.2% 65.5%

EXAMPLE 2 ANHYDRIDE/EPOXY CLEAR

[0055] Parts by Weight Part I anhydride oligomer (Procedure 4) 763.08TinuvinÒ 384 (UV screener from Ciba Geigy) 19.08 TinuvinÒ 292 (hinderedamine light stabilier 13.74 from Ciba Geigy) 5% BYK-301Ò (flow additivefrom BYK Chemie) 56.4 in PM acetate 25% tetra butyl phosphonium chloride19.84 in PM acetate butyl acetate 97.0 Part II diglycidyl ester ofcyclohexane dicarboxylic acid 358.65

[0056] This coating was sprayed over a black waterborne basecoat whichhad already received a warm air flash of 5 min at 82° C. The coating wascured for 30 min at 141° C. This coating exhibited excellent appearance,hardness, cure and durability. This coating exhibited significantlybetter durability than a similar coating based on a standard acrylicanhydride polymer (a 6,000 weight average molecular weight polymercontaining 27% itaconic anhydride). The acrylic was substituted for theoligomer on an equivalent basis. On accelerated QUV testing (using anFS-40 bulb), the polymeric anhydride based coating cracked after4,000-6,000 hours of exposure; the oligomeric based coating showed nocracking and had excellent gloss at over 10,000 hours of exposure.

EXAMPLE 3 MELAMINE CLEAR

[0057] Parts by Weight Part I tetra hydroxyl functional oligomer 16.1(Procedure 1) di hydroxyl functional oligomer 16.6 (Procedure 2) CymelÒ1168 (melamine from Cytec Ind.) 16.1 20% BYK-301Ò (flow additive fromBYK Chemie) 0.4 in PM acetate catalyst solution* 0.8 *catalyst solutionCycatÒ 600 (sulfonic acid from American Cyanamid) 48.0 AMP-95Ò (aminefrom Angus Chemical) 10.8 methanol 41.2

[0058] This coating was applied over a black waterborne basecoat whichhad already received a warm air flash of 5 min at 82° C. The coating wascured for 30 min at 141° C. This coating exhibited good appearance,hardness, and mar resistance.

EXAMPLE 4 SILANE (a)/HYDROXYL (b)/ISOCYANATE (c)

[0059] Parts by Weight Part I tetra hydroxyl functional oligomer 243.5(Procedure 1) hydroxyl/silane oligomer 175.9 (Procedure 3) TinuvinÒ 384(UV screener from Ciba Geigy) 9.47 TinuvinÒ 292 (hindered amine lightstabilier 6.97 from Ciba Geigy) 10% BYK-301Ò (flow additive from BYKChemie) 3.29 in PM acetate 10% di butyl tin dilaurate in butyl acetate1.04 butyl acetate 26.3 PM acetate 26.3 Part II TolonateÒ HDT(isocyanurate turner of 157.2 hexamethylene diisocyanate fromRhone-Poulenc)

[0060] This coating was sprayed over a black waterborne basecoat whichhad already received a warm air flash of 5 min at 82° C. The coatingexhibited excellent appearance, hardness and mar resistance.

EXAMPLE 5

[0061] A.) Nonaqueous Dispersion

[0062] To a 5-liter flask fitted with a agitator, thermometer, condenserand addition funnels was added the following ingredients. The mixturewas agitated under nitrogen and temperature raised to reflux (100° to104° C.). Ingredients are given in parts by weight (to the nearest wholenumber, for most). The dispersed polymer is 63.5% weight solids intoluene having a weight average molecular weight of 8100. Thecomposition was as follows: STY(BA/BMA/HEA/MAA/GMA(14.7/43.6/27.5/10.1/2.3/1.7) dispersed polymer 206 isoprapanol 12spirits 94 heptane 53 butanol 3

[0063] Added as a shot at reflux was t-butyl peroctoate (0.5 parts) andmineral spirits (5 parts). Then, the following ingredients were addedover a 210 minute period at reflux: styrene 52 hydroxy ethylacrylate 86methyl methacrylate 126 glycidyl methacrylate 5 methacrylic acid 14methyl acrylate 62 dispersed polymer 103

[0064] These ingredients were added next and the reaction held for 45minutes: butanol 12 heptane 17 t-butyl peroctoate 5 mineral spirits 31

[0065] Butanol (16 parts) and t-butyl peroctoate (1.7 parts) were thenadded over a 30 minute period and the reaction was held for 60 minutes.Finally, the reactor was stripped of 76 parts of solvent. The particlesize was 298 nm as measured by quasielastic light scattering and had aroom temperature viscosity of 2000 centipoise at 5 rpm on a Brookfieldviscometer and a weight solids of 63.5 percent.

[0066] B.) Acrylosilane Resin

[0067] The resin was made by this procedure: charge 400 g of 2 ethylhexanol and 400 g of N-pentyl propionate to a 5 liter flask. Heat toreflux. Premix and add 896 g of styrene, 672 g of gamma methacryl propyltrimethoxy silane, 336 g of 2-ethyl hexyl methacrylate, 336 g ofhydroxypropyl methacrylate, 170.2 g of 2.2(2 methyl butane nitrite), 40g of 2 ethyl hexanol, and 40 g of N-pentyl propionate to the refluxingmaterial over a period of six hours. After the addition, hold thetemperature for 30 minutes. Then, add a premixed blend of,40 g of 2ethyl hexanol, 40 g of N-pentyl propionate and 9 g of 2.2(2 methylbutane nitrile) over a 30 minute period. Hold the temperature for 30minutes after addition, then cool and empty. Gardner Holt ViscosityWeight Solids Weight Ave. M.W. X + ½ 73.3% 5686

[0068] C.) Cyclosilane Oligomer (i)

[0069] Place some cyclohexanedimethanol in the oven to melt. Oncemelted, take 294.7 g of cyclohexanedimethanol along with 0.11 g FascatÒ420 (tin catalyst from Elf Atochem) and place in a flask at about 35° C.Then, add 839 g of isocyanate propyl trimethoxysilane over 75 minutes.Then hold for two hours. Cool and empty. Gardner Holt Viscosity WeightSolids Weight Ave. M.W. V 90% 1550

[0070] D.) Silanated Star Polyester (i) Step I: Add the followingingredients to the reactor, heat to 120° C.-125° C. Allow batch toexotherm to 145° C. If exotherm does not happen heat to 145° C. Hold for1 hour at 145° C. before proceeding. Ingredient Weight pentaerythritol280.2 4-methyl hexahydrophthalic anhydride 1037.8 butyl acetate 161.1

[0071] Step II: Feed the ingredients over 30 minutes at 145° C. Maintainthe 145° C. temperature. Cardura E (monoepoxy from Shell Chemical)1561.9 butyl acetate 182.3

[0072] Step III: Add as a shot to reactor. Heat to 175° C. Record AcidNumber vs. time profile, every 30 minutes after reaching 175° C., untilit stabilizes. dibutyltin dilaurate 2.9 butyl acetate 71.7

[0073] Step IV: Once acid number has stabilized, cool to below 100° C.Dilute with butyl acetate. butyl acetate 302 Batch Total 3600

[0074] In a reaction flask, place 3720 g of the star polyester madeimmediately above, 1524 g of isocyanate propyl trimethoxysilane and 0.1g Fascat 420 catalyst. Stir for 90 minutes. Blanket the whole time withN₂.

[0075] wt. solids=86.3

[0076] Wt. Ave M.W.=2200

[0077] E.) Clearcoat Composition Grams E.) Clearcoat Composition GramsResimine{grave over (ο)} 6550 14.43 (melaniine from Monsanto) NonaqueousDispersion (A) 26.77 Acrylosilane Resin (B) 11.6 Cyclositane Oligomer(C) 22.22 Silanated Star Polyester (D) 23.17 Catalyst Solution* 3.55Dibutyltin Dilaurate 0.2 Resiflow S{grave over (ο)} 0.4 (acrylic flowagent from Estron Chemical) Tinuvin 384 2.32 (UV Screener from CIBAGeigy) Tinuvin 123 2.2 (Hindered Amine light stabilizer from CIBA Geigy)*Catalyst solution Cycat{grave over (ο)} 600 (sulfonic acid fromAmerican Cyanamid) 48.0 AMP-95{grave over (ο)} (amine from AngusChemical) 10.8 methanol 41.2

[0078] This coating was applied over a black waterborne basecoat whichhad already received a warm air flash of 5 min at 82° C. The coating wascured for 30 min at 141° C. This coating exhibited good appearance,hardness, etch and mar resistance.

1. A curable coating composition of a binder in an organic solvent, thecomposition having a volatile organic content not exceeding about 0.4kilograms per liter, comprising: i) a binder selected from a linear orbranched cycloaliphatic moiety-containing oligomer or blend of oligomerswith a weight average molecular weight not exceeding about 3,000, apolydispersity not exceeding about 1.5 and functionality A or A plus B;and ii) an optional oligomeric crosslinker or blend of crosslinkers witha weight average molecular weight not exceeding about 3,000 andfunctionality C or C plus D;: components i and ii reacting at cure toform a three-dimensional network having chains of substantially uniform,controllable molecular weight between crosslinks; wherein: A is selectedfrom the group consisting of hydroxyl, anhydride, acid, epoxy, aldimine,ketimine and silane; B is selected from the group consisting of hydroxyland epoxy; C is selected from the group consisting of isocyanate,melamine, epoxy, silane and acid; and D is selected from the groupconsisting of hydroxyl and melamine.
 2. A composition according to claim1 wherein there are components i) and ii).
 3. A composition according toclaim 1 wherein component i) contains functionality capable ofcrosslinking with itself, there being no component ii).
 4. A compositionaccording to claim 1 wherein the oligomer of component i) comprises anoligomeric ester.
 5. A composition according to claim 1 whereincomponent ii) has a polydispersity not exceeding about 1.5.
 6. Acomposition according to claim 1 selected from the group consisting of:A is hydroxyl and C is isocyanate; A is anhydride or acid and C isepoxy; A is epoxy and C is isocyanate; A is hydroxyl and C is melamine;A is aldimine or ketimine, B is optionally hydroxyl, and C isisocyanate; A is epoxy, B is hydroxyl and C is isocyanate; A is silane,B is hydroxyl and C is melamine; A is acid, B is hydroxyl, C is epoxyand D is melamine, and A is silane, B is epoxy, C is acid and D ismelamine.
 7. A composition according to claim 1 additionally containing(i) up to 30 percent by weight of total binder of an acrylic polymer orpolyester with weight average molecular weight greater than 3,000; or(ii) up to 30 percent by weight of total binder of a noncyclic oligomerwith a weight average molecular weight not exceeding about 3,000, apolydispersity not exceeding about 1.5 and functionality A or A plus B;or (iii) up to 30 percent by weight of total binder of an acryliccomponent comprising a core of acrylic polymer and, grafted thereto, aplurality of substantially linear stabilizer components, this componentcontaining at least about 2 percent of ethylenically unsaturated monomerwith functionality capable of reacting with (i), (ii), or both (i) and(ii), the core being substantially insoluble and the stabilizercomponents being soluble in the solvent medium.
 8. A compositionaccording to claim 1 additionally containing up to 200 parts by weight,based on 100 parts of (i) and (ii), of pigment.
 9. A method for coatinga substrate comprising applying thereto a composition according to claim1 and curing the composition.
 10. A substrate coated with thecomposition of claim 1.